emit: Unwind the definitions for typedefs in type__emit_definitions()

For instance, with the existing code we ended up with:

  typedef __kernel_size_t size_t;
  size_t tcp_opt_stats_get_size(void)
  {
  }

Which lacks unwinding what a __kernel_size_t is, i.e.
type__emit_definitions() was only emitting definitions for the members
of structs and unions, do it for typedefs too, and then we end up what
we need, which is:

  typedef long unsigned int __kernel_ulong_t;
  typedef __kernel_ulong_t __kernel_size_t;
  typedef __kernel_size_t size_t;
  size_t tcp_opt_stats_get_size(void)
  {
  }

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

dwarves_emit.c

@@ -294,6 +294,9 @@ int type__emit_definitions(struct tag *tag, struct cu *cu,
 		return 0;
 	}
 
+	if (tag__is_typedef(tag))
+		return typedef__emit_definitions(tag, cu, emissions, fp);
+
 	type_emissions__add_definition(emissions, ctype);
 
 	type__for_each_member(ctype, pos)